1. Field of the Invention
The present invention relates to an optical pointing device and, more particularly, to an optical pointing device which improves a structure of a diaphragm to cover portions other than a significant surface of a lens, thereby preventing stray light from entering a lens.
2. Description of the Related Art
In general, a pointing device for a computer is a peripheral device of the computer which indicates its location using a cursor. The pointing device is classified into a ball pointing device which detects motion thereof using a ball installed therein and an optical pointing device which detects motion thereof using reflectance of light irradiated from a light emitting diode installed therein.
The conventional optical pointing device, as shown in FIG. 1, includes a light emitting diode 6 installed inside a case 9 which has an opening portion 8 formed at a bottom portion thereof, a prism 7 for reflecting light irradiated from the light emitting diode 6, a lens 2 into which the light that is reflected from the prism 7 and then reflected by a pad or floor 3 is collected, an image sensor 5 for receiving the light collected by the lens 2, and a diaphragm 1 which is arranged below the image sensor 5 and shields stray light to thereby allow the image sensor 5 to receive the light collected on a significant surface of the lens 2.
Here, the diaphragm 1 is fixed below the image sensor 5.
In the conventional optical pointing device described above, the reflected amount of light irradiated from the light emitting diode 6 installed in the case 9 is collected by the lens 2, and the image sensor 5 receives the reflected amount of light through the diaphragm 1 to detect motion for an x axis and y axis directions of the optical pointing device.
However, the conventional optical pointing device has a disadvantage in that the diaphragm 1 should be remade to use different-shaped or different-sized lens 2 since the diaphragm 1 is fixed below the image sensor 5.
Also, since the diaphragm 1 is coupled to the image sensor 5 such that the diaphragm 1 and the lens 2 have a predetermined distance “d” therebetween, an optical angle that light can enter through the diaphragm 1 is increased as much as the distance “d” between the diaphragm 1 and the lens 2, so that a large amount of stray light may enter the image sensor 5 through the diaphragm 1.
That is, the optical angle is so large such that the light which enters through portions other than the significant surface of the lens 2 may be received by the image sensor 5, thereby increasing an error of motion for the x axis and y axis directions of the optical pointing device.